For example, a driving assistance device disclosed in Patent Literature 1 has been known as a device for assisting the driving of a host vehicle. Patent Literature 1 discloses a lane keeping device which generates steering torque in order to maintain the traveling position of the host vehicle in the lane, for example, when the host vehicle is likely to deviate from the traveling lane. In addition, a driving assistance device disclosed in Patent Literature 2 has been known as the device for assisting the driving of the host vehicle. Patent Literature 2 discloses a control unit which detects the carelessness of the driver on the basis of a variation in the angle of a steering wheel due to a steering wheel operation of the driver and issues a warning when the carelessness is detected.